Levator Palpebrae Superioris

The levator palpebrae superioris broadens into a wide bilaminar aponeurosis as it approaches its distal attachments. The superficial lamina attaches to the skin of the superior eyelid, and the deep lamina to the superior tarsus. This muscle is opposed most of the time by gravity and is the antagonist of the superior half of the orbicularis oculi, the sphincter of the palpebral fissure. The deep lamina of the distal (palpebral) part of the muscle includes smooth muscle fibers, the superior tarsal muscle, that produce additional widening of the palpebral fissure, especially during a sympathetic response (e.g., fright). However, they seem to function continuously (in the absence of a sympathetic response) because an interruption of the sympathetic supply produces a constant ptosis - drooping of the upper eyelid.